Many industrial endeavors result in the creation of effluent or liquid waste which can be characterized as an oily substrate and which can require treatment for component recovery and potential reuse and/or disposal of waste components depending on environmental concerns. Many industrial processes economically depend upon recycle of component materials. Further, recent and proposed environmental laws and regulations increasingly place an environmental consciousness and stress upon producers of oily material waste, and regulations have changed causing disposal methods which had previously been acceptable to become unacceptable from an environmental viewpoint.
Oily substrates as wastes generally involve mixtures of water and oily materials such as hydrocarbons including potentially hazardous components such as polychlorinated biphenyls, benzene, toluene and the like and can additionally contain solids. A common source of such oily substrates is due to oil and gas industry activities in exploration, production, refining and petrochemical production. Oily substrates are created at the well head in deep well injection systems in the form of residue from drilling mud and production water. Oily substrates also created in refineries in many different forms from water collected in storm sewers at a refinery to streams from the refining process. Oily substrates are also created in the cleaning of transport trucks and rail cars which move crude petroleum and oil products. Moreover, oily substrates are created in the same manner in chemical plants which involve the processing of petroleum products and which involve the manufacture of chemicals and chemical products for distribution and sale. Nearly all of these oily substrates have common characteristics. For example, they routinely contain, as components, solids, usually in a small amount, and oily materials which contaminate both the solids and water. Oily substrates also typically exist in the form of emulsions comprising solids, oily materials and water, or oil-in-water or water-in-oil emulsions. Water is normally present and at times can make up a large part of the oily substrates. The presence in these oily substrates, particularly of large amounts of water, often emulsified with the oily material present, compounds the difficulty and expense with respect to separating these materials into components for either recycle use or environmentally acceptable disposal.
Many attempts have been made to deal with this problem in order to be able to remove or separate the oily materials present, to recycle reusable components or, to dispose of environmentally detrimental materials and to limit the resultant liability of the generator or owner of the oily substrate as a waste and waste disposal site.
Several varieties of treatment techniques are known involving various solvents and approaches to remove or separate the components in oily substrate type effluent or hazardous waste. For example, one such attempt at separating materials for disposal is described in John H. Moses, "Use of Liquified Gas Solvent Extraction in Hazardous Waste Site", presented at the AICAG 1988 Summer National Meeting in Denver, Col., August 1988, wherein sludges containing oil, water and solids are treated under high pressures with propane in a gaseous treatment process. The pressurized extraction of the oil or hydrocarbon is followed by a separation of water and solids with the propane solvent being recovered by flashing it off as a vapor in a flash tank. The solvent is then recovered, repressurized and returned to the process. This gaseous solvent process thus is distinguished from liquid solvent treatments which require separation by distillation. However, while simple in concept, the above-described process as well as other conventional processes are yet to be successfully applied to the clean-up of sludges, as, often the solids in sludges and oily substrates comprising solids in general tend to agglomerate when conventional treatment procedures are attempted thus trapping oily materials within the solids mass preventing contact with the solvent used for oily material removal.
Although attempts made in the art to clean such oily material wastes have been admirable, problems still remain in connection with the processing of such materials in an environmentally safe manner for reuse or disposal. Heretofore, waste effluent and sludges in particular with oily materials present and containing large quantities of water could not be economically treated and the components thereof separated and such oily substrates are usually disposed of via land disposal techniques. However, current environmental legislation and regulations ban use in the future of land disposal techniques.
Also, oily substrates in the form of emulsions of oil-in-water and water-in-oil, for example formed during oil production operations or in petrochemical processing, also present heretofore unsolved treatment problems for recycle and waste disposals.
If treatment can occur at locations where oily substrates are generated and some of the components thereof, such as solids and water, can be disposed of on site after processing, considerable savings can result compared to hauling the oily substrate as a waste to another location for disposal.